Greenhouse films are widely used films which retain heat inside greenhouses to ensure there is sufficient warmth for plant growth. In order to reduce the heat loss at night, good IR absorption capability is required for a greenhouse film. The wavelength of the ground IR radiation is mainly in the 7-14 μm region, thus adding a suitable IR absorber with a strong IR absorption in the 7-14 μm wavelength region can enhance the IR absorption and heat retention of the film. The conventional approach for heat retention improvement is adding ethylene vinyl acetate (EVA).
EVA demonstrates good IR absorption in the 7-14 μm wavelength region. However, the EVA content in the film is usually very high in order to achieve adequate IR absorption. This increases the film costs and results in poor mechanical properties, such as tensile strength, tear strength, etc.
As a result, there may be a continual need for improved films which provide heat retention and IR absorption, while maintaining desirable mechanical strength properties in the film.